Children with intellectual disability often display severe destructive behaviors (e.g., aggression, self-injurious behavior) that pose significant risk to self or others and represent overwhelming barriers to community integration. These destructive behaviors are often treated with behavioral interventions derived from a functional analysis (FA), which is used to identify the environmental antecedents and consequences that occasion and reinforce the target response. One such treatment is called functional communication training (FCT), which involves extinction of destructive behavior and reinforcement of an alternative communication response with the consequence that previously reinforced destructive behavior. Results from epidemiological studies and meta analyses indicate that interventions based on FA, like FCT, typically reduce problem behavior by 90% or more and are much more effective than other behavioral treatments. Despite these impressive findings, FCT interventions reported in the literature have typically been developed and evaluated by highly trained experts in tightly controlled research settings, and treatment relapse (i.e., increased destructive behavior) often occurs in the natural environment when a caregiver is unable reinforce the FCT response due to competing responsibilities (e.g., caring for a sick sibling). Behavioral momentum theory helps to explain why treatment relapse occurs under these circumstances and also provides mathematical equations that can be used to model and predict the variables that increase and decrease the likelihood that treatment relapse will occur. In the current project, we have used these equations to identify several potential refinements to FCT that are likely to markedly decrease the probability that treatment relapse will occur when the FCT response is not reinforced. In some cases, these refinements are at odds with what is recommended in the clinical literature on FCT. Therefore, it is critically important that we compare these refinements that are derived from behavioral momentum theory with current clinical practice in order to determine the best way to implement FCT, so that treatment remains effective when it is implemented with less than perfect precision by caregivers in the natural environment.